The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Navigation software available today cannot provide precise reliable navigation inside tunnels. More generally, geopositioning systems that rely on signals from satellites, such Global Positioning Service (GPS), do not work in areas where these signals are completely or substantially occluded by obstacles. Some devices in these situations rely on dead reckoning, or estimation of a change in position based on the speed at which the device is moving. However, dead reckoning accumulates errors, and accuracy quickly diminishes with changes in speed.
Meanwhile, navigation in tunnels remains a relevant problem as drivers often slow down and sometimes even come to a complete stop when checking for underground exits or turns. Especially as more and more drivers today become dependent on navigation systems telling them where and when they should turn, reliable geopositioning everywhere along a route, including inside tunnels, is important.
To use low-energy signal sources such as Bluetooth® or Wifi™ “beacons,” or Wifi™ access points, for geopositioning in areas with limited satellite coverage, the locations of the signal sources must be established prior to geopositioning receivers. Determining locations of signal sources can require land surveying, precise measurements, precise installation, etc. For example, to install signal sources at precisely known locations (or precisely determining the locations immediately upon installation) in general is difficult, time-consuming, and potentially disruptive of the operation of the tunnel.